Process of producing gas.



No. 848,729. PATENTED APR. 2, 1907. v

H. L. DOHERTY. PROCESS OP PRODUOING GAS;

APPLICATION FILED MAY 12, 1906. I

a H \a 23% i aa w 3% attorney UNITED .sTATEs PATENT OFFICE.

HENRY L. DoHERTr, otfiififsot, wIsooNsIN; a t

PROCESS OF PRoDucme- GAS.

Specification of Letters Patent.

Patented April 2, 1907.

" Applic tion filed May 12, 1906, Serial No. 316,535.

To aZZ whio m it may concern:

Be it known that I, HENRY L. DOHERTY, a citizen of the United States,residing in Madison, county of Dane, and State of Wisconsin,

have invented certain new and useful Improvements in Processes ofProducing Gas; and I do hereby declare the following to be a full,clear, and exact description of the same, such aswill enable othersskilled in the art to which it appertains to make and use the same.

This invention relates to processes of pro I ducing gas, and consists ina method of oper- 'method, all as more fully hereinafter set forth andas claimed.

While it is recognized that the operation of gas producerswith-downdraft is at tended with a number of advantages, chemical andphysical, downdraft is seldom used in practice, for the reason that thecoal masspits and channels, causing localized intense combustion with inturn more pitting. The downdraft is in the 'opposite direction to thenatural flow of heated gases, andit is diflicult to induce thedraft-currentto permeate evenly the bed of fuel. With updraft the sametendency to pit and channel exists, though not to the same degree.Acceleratio'n ofdraft is apt to increase this difficulty '5Runningproducers hot with rapid fuels feed-andconsumption and with hotor accetrather than diminish it, andthe same is true of heateddraft-currents. The combustion of carbon increases in velocit with thetemperature, and a spot of loca ized high temperature tends to spreadandincrease insize, the development of heat tending to-form more heatand to develop a pocket; -:As=a pocket'forms the air tends to follow,aggravating the trouble and also making 'itidgikely that air willpenetrate the fuel mass -without contacting or contactingfon aninsuflicient time for full 'reaction,-thereby stratifying the resultantgas or burning with it to produce useless carbon dioxid-Q erated draft,though obviously advantageousasgiving greaterout ut, has hitherto beenconsidered undesirab e,;both.fo'i' the producer temperatures all havelimitations foregoing reasons and 'because of certain purely incidentaldisadvantages with most coals caused by-the fusibility of their ashresulting in such .high temperature, rapid o eration in slagging, orsintering ofsuc'hjas Conditions in the producer generally have to beadapted to the peculiarities of the coal-Y ash rather than to the needsof the gas-making process proper, and many' coals otherwise suitable aredeemed unavailable because having fusible ash. Nor in the ordinarypractice is theremuch elasticity in response to sudden demands'forlarger quantities of Blast velocities, coal consumption, and

which it is deemed unwise to exceed, there being a certain limitingnumber of pounds ofcoal which can be converted per s uare foot 0fcross-section without danger of c inkering,

injuring grate-bars, or channeling the fuel mass.

' It is the object of the present invention to obviate the stateddisadvantages and enable producers to be run at comparativel'hightemperatures in gasifying zones, to uti ize more of the cubiccapacity of'a gas-producer, toemploy high-velocity draft-cur rents andconvert more coal per unit of time,

and to use a downdraft without fear of pocketing. In the resent methodinstead of endeavoring to cop temperatures in the ignited zones of thefuel at a point below the clinkering temperature of the ash, as iscustomary,

the fusibility of the ash is disregarded and operation in thesegasifying zones is at comparati'vely hlgh temperature, the specialdegree depending upon the character of the gassought. There is adifference in the charaeter of gas corresponding to every s eci'altemperature, An automatic metho formaintaining the temperature in thegasifying zones at any desired given point is herein after described. 4x

In the usual operation with updraft the incoming air first meets thecoal in the im- -mediate vicinity of the ash. The first layer burned isthat which is more or less mixed with 'suchfash. This is also-themaximum temperature deve ops and the resuit, with a pure-air draft, is at to be a sin oint where the m5 tering of the ash and otherisad'vantages;

Acceleration of the draft-current or the use I of heated draftincreases'these difiiculties;

The ash particles are finely divided, chem,

between layer really clean, and in close juxtaposition to each otherallconditions. which tend to promote formation of clinker. 1n the fuelitself, on the other hand, the ash particles are not in contact and arerelatively remote from each other. They are, so to speak, separator orinsulated from each other by the particles of the fuel itself. In such aposition it is quite immaterial how high a heat they be subjected to.They may be, of course, melted to thin fluidity or any degree short ofthat point without the least danger of their agglomerating together toform, clinker or slag as long as they are kept separate. Therefore ifthe draft-current be introduced in the same direction as the coal, as ina top-fed downdraft producer the producer may be operated ashot as maybe desired and with hot or rapid draft, so long as the excessively hightemperatures do not extend to the ashbed. Of this there is little'dangerwith a deep bed of fuel, provided channeling or formation of pit-holescan be avoided. This may be done by an expedient later described, andthis expedient makes it even possible to extend the zone of hightemperature farther into the fuel-bed than is usually done not onlywithout risk, but with manifest, advantage. Such extension of thehigh-temperature zone is desirable as increasing the output and capacityof a producer. In the usual operation intense heat is produced in thefirst layer exposed to the draft, carbon dioxid being there formed witha pure-air draft, and

this dioxid is again reduced in the next layer with absorption of heat,The result is that in such ordinary operation the temperatures rap'idlydecrease away from the first glowing layer of fuel. Thev temperaturegradations and layer are very sharp, with the result that the usefulwork of theproducer is ordinarily done by a comparatively thin stratum.Therefore in certain embodiments of this invention it is preferred todiminish the rate of this cooling effect byaccelerating thedraft-current and feeding to the first glowing layer at a rate fasterthan the fuel in this layer can react therewith, thereby carryingsensible heat and carbon-oxidizing gases into remoter layers. Suchheating of the remoter layers, however, is not allowed to extend to theash accumulation in a degree which would tend to produce clinker. Theobject is to produce an evener gradation of heat throughout the fuelmass without the sharp changes in temperature found in the usualmethods.

Using high-blast velocities and high temperatures in the draft-current,high temperatures are createdin the first glowing layer of coal, whichin the case of the eight or ten inches beneath the layer of fresh fuel,and with coals having fusible ash the ash particles often melt in thecoke, forming downdrafto eration now under description is usual y smallglobules or rounded particles. As the carbon around them disappearsthese sink downward, and in'passing through layers of with pure airbeing great, itis difficult to produce the regulated distribution ofheat throughout thefuel mass with-a pure-air draft; but it may easily bedone with an airdraft containing an endothermic constituent which willdamp combustion more or less. Such a draft-current is found in the oneused to restrain pocketing or channeling-a mix ture of air withrelatively high proportions of carbon. dioxid or products of combustioncontaining the same. Waste gases from operations decomposingcarbonates-as in burning lime, making glass, smelting iron, and thelikecancontain more carbon dioxid than ordinary products of combustionand are particularly useful in this connection. VVithsuch adraft-current containing dioxid in relatively large proportion thetendency to pocket is obviated by an automatic chemical reaction, andtheutilization of this reactionis a material aidin making possible to usehigh'temperatures, high speed of draft, and quick operation withextension of reaction through the fuel mass to obtain high duty from theproducer.

In the reduction of carbon dioxid to car bon monoxid by glowing carbonthe velocity of the reaction is a function of the prevailing temperatureand increases more rapidly than The velocity of the combustion of carbondoes the temperature with arise in heat I that is, the higher thetemperature the more dioxid is reduced in a 'unit of timebut thereaction is attended with absorption of heat,

andconsequently the greater the tempera ture the more heat is absorbedin a unit of time and the more the temperature tends to fall, andconversely. The speed of reaction, further, also depends upon theconcentration of the carbon dioxid in. the draft-current or its partialpressure. The greater this partial pressure the more will be reduced ina unit of time. The chemical chilling which results from the reductionof coursecan be compensated for, wholly or in part, by impartingsensible heat to the draft-current.

- It will be seen that with a rapid draftcurrent containing much carbondioxid and kept at a given temperature the reaction is automatic andself-checking, rise or fall of temperature in the-fuel mass above orbelow a fixed point being restrained. These propof this invention.

erties are much more apparent with the produeerrun at the relativelyhigh temperatures employed in the preferred embodiment By regulating theproportion of endothermic constituent in the draft-current, regulatingthe temperature with which it strikes the first ignited layer of fuel,and regulating its speed I can maintain substantially any temperaturedesired with in a wide range in said layer. Heating'the draft -currentand increasing its content of carbon dioxid tend to compensate eachother,

and by raising the temperature to a suflieient degree it can be made tocarry very large per cents of dioxid. In this .relation it is possi ble'to use a balanced draftcurrenti. e., one in which the air and theendothermic constituent neutralize thermally each other in their actionupon the fuel, and the fuel in 4 the reducer therefore remains in astatic con ition so far as the influence of the drafteurrent isconcerned. In such an event it is necessary to supply the draft-currenthot.

This heat may be derived from the heat of the issuing vices.

With a draft-current containing large proportions of carbon dioxid ifthe fuel begins to heat above the desired degree the reduction of dioxidand chilling are more than proportionately accelerated and thetemperature isbrought backto the desired point,

gas by theusual regenerative deor if the fuel cools somewhat reductionof dioxid in the surface layers diminishes somewhat and the temperaturerises. With each glven draft-current of given temperature a definitetemperature will be established in a given mass of coal andautomatically tend to remain constant. This which is true of the mass isalso true of individual spots, and if such a spot begins to burn hot anddevelop a pit-hole the increased reduction of dioxid quickly brings backits temperature to the general average.

By the described method the producer may be run at any temperatures andthe excessively-highdegrees hitherto precluded by c oa on the top layerand carries the distilla- ..t1on products down into the ignitedlayersfor cracking. Further, as carbon dioxid has ,a specific damping actionon the reaction of oxygen and carbon, materially slowing it in point oftime, it is 'easy with the described draft-current to carry much of thesame 'unchangedinto deep layers of the fuel beyond the first glowinglayer, This passing current carries with;it much sensible heat, andthis,

together'with the heat evolved by the un-' changed oxygen, suffices toinstitute the gasmaking reaction in such deeper layers{ Preferablydraft-current speed, temperature, and composition are so regulated as tomaintain a gradually-decreasing tem eraturefrom the ver hot firstglowing ayer down to the layer of 'uel next the ash-accumu lation, thislatter layer being kept as hot as may be withoiit clinkering said ash-'There is an additional advantage in rushing the draft-currents throughthe. fuel mass at the speeds described, in that it enables, if desired,some of the draft-current to mix with the produced gas, thereby givingcombustible gases of any desired regulated length of flame and speed ofcombusiton, even to gases so weak as to be incapable of burning withoutheated air or radiant heat. Such gases are useful in many arts. In theirproduction it is .ordinarily desirable to pass both oxygen and carbondioxid through the fuel mass to become admixed with the gas. Though thegas has both oxygen and combustible in it,

the influence of the carbon dioxid prevents much combustion, and it maybe readily cooled and conveyed to a place of' use. To

obtain a gas of this character, a very rapid draft-current containinglarge roportions of carbon dioxid should be emp eyed, such as s eed oftravel being employed as'to cause the (esired amount ofsuchdraft-current to go through the deep bed of fuel unchanged. Using a deepbed of coke or other fuel, a

gas can be obtained of any desired rate of combustion or flame volume.Incidentally, ofcourse, the other advantages of temperature re ulationin the producer and extended conversion of fuel are also obtained.

Brieflystated, the present invention, .in the embodiment now preferred,consists in establishing a deep bed or other large mass of incandescentfuel and traversing it with a lID draft-current flowing in the samedirection as.

containing much carbon dioxid or other endothermic constituent and beingsupplied under accelerated draft; in maintaining the first ignited layerof fuel at a very high temperatureplane, even-so highas to freely fuseash ingredients therein, and maintaining subsequent layers at a high butless temperature, with gradual diminution to the'iash accumulation.Preferably the draft-current is supplied hot and containin an amountofcarthe feed of fuel, said draft-current preferably bondioxidsufficient to c ecklocalized undue developments of heat, and incombination with the heat of the. draft and the exothermic action oftheair thereofto maintainthe' temperature of the said first-ignitedlayer at a desired point,'and in combination alsqwithi the velocityofthe current to maintain the-- graded heat of remoter layers in themanner venting channeling is applicable to any pro- I La) thetemperature rise of the ducer whether operating under high or lowtension or. up or down draft. By regulatlng the relatlons oftemperature, compo'sitlon,

and speed of the draft-current any desired temperature may beautomatically set and maintained in the first-ignited layer and also insubsequent layersand channeling prevented. I

With a given draft-current supplied at a given velocity and giventemperature to a mass of given fuel there will be a definite temperatureand temperature gradation set up in the mass offuel. Should thetemperaof autom atieally I ture of the fuel-bed increase at anyparticular point or throughout, the rapidity with which the reduction ofcarbon dioXid takes place will be, accelerated at'a rate greater thanthe rise in temperature, provided'the percent-age of carbondioxid in thedraft-current remains constant, regardless of the tension at which theproducer is operated. In this manner fuel-bed is 0pposed by an everincreasing reduction of car- -bon di oxid and ever-increasing chemicalchilling. On the other hand,' if the temperature tends to fall thereduction of carbon dioxid, and consequently the chilling, decreases ata more rapid rate than the fuel-body cools off. The method of adjustingthe flame volume of a gas yielded by a producer by increasing ordiminishing the amount of the draft-current rushed through the fuel massis also of course applicable to any producer. It is merely a matter ofadjusting-the composition of the draft-current'and its rate of travel toproduce'with any deep'bed' of fuel a gas of a given rate or burning orflame volume.

In the accompanying illustration is shown more or less diagrammaticallyapparatus suitable for carryii'ig out this process.

In the drawings, 1 is a gas-producer pr0- vided with the usualfeed-hopper 2 and having a gas-outlet 3 near its base. As shown, thisgas is delivered into a puddling-furnace 4, diagrammatically shown.Intensely-hot products of combustion from rise through stack. 5,containing a stack air-heater 6. through pipe 8, which enters draft-pipe9, having a jet-nozzle 10 therein. The draftpipe taps the stack at 11,drawing off said this furnace Air is furnished to the heater currentpassing through the fuel unchang 1 nioter layers of fuel and yielding agas stack-gases therefrom by the injector action of the air-jet. It isprovii'led with damper 12 and an auxiliary air-inlet 13, open directlyto the atmosphere and controlled by valve 14.

By proper adjustment/of these valves and of the force of air-jet,mixtures of air and products of combustion of any desired nature may beintroduced into the producer above the fuel therein.

What I claim is l. Inthe operation of a downdraft gas-producer, theprocess which consists in maintaining the first-ignited layers of fueltherein at a temperature sullicieint to fuse ash in gredients and lowerlayers 'at a gasifying temperature below said first-stated tei peratureby an accelerated draft-current of connningled exothermic andendothermic components traversing said first-ignited layers at a speedgreater than the reactive rapidity of the same.

2. In the operation of a downdraft gas-producer, the recess whichconsists in maintaining the iir'st-ignited layers of fuel therein at atemperature su'iiicient to fuse ash in.-. gredients and lower layers ata gasifying temperature below said first-stated temperature by a hotaccelerated draft-current of conimingled exothermic and endothermiccomponents, traversing said first-ignited layers at a speed greater thanthe reactive rapidity of the same.

3. In the operation of a downdraft gaspro ducer, the process whichconsists in maintaining the first-ignited layers of fuel therein at atemperature sufficient to fuse ash irgredients and lower layers at agasifying'tenierature below said first-stated temperature liy a hotaccelerated draftcu'rrent of commingled exothermic and endothermiccomponents in thermally-bale cing proportions traversing saidfirst-ignited i'ayers at a speed greater than the reactive pidity of thesame, recovering heat from te outfiowing gas and adding it to theinflowing gases.

L'The process of producing gas which consists in establishing andmaintaining a.

deep bed of hot fuel and transmitting through the same an accelerateddraft--cur rent of commingled air and'products of coinbustion at avelocity sufiiciently great to insure a regulated proportion of'saiddraftthereby imparting sensible heat to th ii.-

regulated dilutim.

. 5. The process of producing gas which consists in establishing andmaintaining a deep. bed of hot fuel and transmitting through the sameunder accelerated velocity 8 hot draft-current of commingled air andproducts of combustion in the same direction as the feed of fuel, thetemperature of said draft-current being maintained sidlicientlv high topermit fusion of ash ingredien in the ICC lIO

1 portion thereby first-ignited layers of the fuel and its velocitybeing sufficiently great to-insure a regulated passing through the fuelunchanged,

imparting sensible heat. to the underlying layers of fuel and yielding agas of regulated dilution. I

6.- The process of producing gas which consists in establishing andmaintaining a deep bed of hot fuel, and in transmitting therethrough ahot draft-current of cornmingled air and products of combustion atsufiicient velocity to insure a regulated portion going through the fuelunchan ed,

I thereby yielding a gas of regulated dilut1on.

speed of the first-ignited layers.

7. The process of producing gas which consists in establishing andmaintaining a deep bed of ignited fuel and in transmittmg downwardthrough the same an accelerated draft-current of commingled air androducts of combustion at a suflicient ve ocity to .cause' reactionthroughout the depth of said bed, said-draft-current traveling at aiieater speed than the reaction speed of the st-ignited. layers. 8. Themethod of'heating reinoter layers I of fuel in a deep bed of fuel whichconsist-s in transmitting through said fuel a draft-current at avelocity greater than the reaction 9.- In the operation of agas-producer, the method of obviating channeling in the fuelbed whichconsists in transmitting through the fuel-bed a draft-current rich incarbon dioxid at a speed greater than the reactive speed of thefirst-ignited layers.

1 ward through theignited fuel greater than the reactive speed of themic and 1 endothermic 10. The process of consists in establishing andmaintaining a deep bed of ignited fuel, mingling air with products ofcombustion to roducea draftcurrent, and feeding said dra -current downata s eed stignited layers with the components of the draft-current and ata speed sufficient to cause reaction throughout the entire depth of saidbed. p v

11. The process of producing gas which consists in establishing andmaintaining a producing gas which deep bed of hot fuel andtransmittingthere through a hotin'combustible draft-currentoflcomrmngled air and products of combustion in exothermic and endothermicbalance, the

sensible heat of the draft-current being s'ufiicient to maintain thetemperature of the producer at a given point and obviate heat osses.

12. The

process of producing gas which consists in establishing and maintaininga deep bed of hot fuel, transmitting therethrough a hot draft-current ofcomniingled air and products of combustion in exotherbalance, recoveringheat from the as producedand adding it to, the infiowing raft-current.

In testimony whereof I aflix my signature in the presence of twowitnessea i HENRY L. DOHER'IY.

Witnesses:

FRED I. SNITH, T. H. FAIR.

